@article{PAR00010825,
  title = {{T}hermal convection in {E}arth's inner core with phase change at its boundary},
  author = {{D}eguen, {R}. and {A}lboussiere, {T}. and {C}ardin, {P}hilippe},
  editor = {},
  language = {{ENG}},
  abstract = {{I}nner core translation, with solidification on one hemisphere and melting on the other, provides a promising basis for understanding the hemispherical dichotomy of the inner core, as well as the anomalous stable layer observed at the base of the outer core-the so-called {F}-layer which might be sustained by continuous melting of inner core material. {I}n this paper, we study in details the dynamics of inner core thermal convection when dynamically induced melting and freezing of the inner core boundary ({ICB}) are taken into account. {I}f the inner core is unstably stratified, linear stability analysis and numerical simulations consistently show that the translation mode dominates only if the viscosity eta is large enough, with a critical viscosity value, of order similar to 3 x 10(18) {P}a s, depending on the ability of outer core convection to supply or remove the latent heat of melting or solidification. {I}f eta is smaller, the dynamic effect of melting and freezing is small. {C}onvection takes a more classical form, with a one-cell axisymmetric mode at the onset and chaotic plume convection at large {R}ayleigh number. eta being poorly known, either mode seems equally possible. {W}e derive analytical expressions for the rates of translation and melting for the translation mode, and a scaling theory for high {R}ayleigh number plume convection. {C}oupling our dynamic models with a model of inner core thermal evolution, we predict the convection mode and melting rate as functions of inner core age, thermal conductivity, and viscosity. {I}f the inner core is indeed in the translation regime, the predicted melting rate is high enough, according to {A}lboussiere et al.'s experiments, to allow the formation of a stratified layer above the {ICB}. {I}n the plume convection regime, the melting rate, although smaller than in the translation regime, can still be significant if eta is not too small. {T}hermal convection requires that a superadiabatic temperature profile is maintained in the inner core, which depends on a competition between extraction of the inner core internal heat by conduction and cooling at the {ICB}. {I}nner core thermal convection appears very likely with the low thermal conductivity value proposed by {S}tacey & {L}oper, but nearly impossible with the much higher thermal conductivity recently put forward by {S}ha & {C}ohen, de {K}oker et al. and {P}ozzo et al. {W}e argue however that the formation of an iron-rich layer above the {ICB} may have a positive feedback on inner core convection: it implies that the inner core crystallized from an increasingly iron-rich liquid, resulting in an unstable compositional stratification which could drive inner core convection, perhaps even if the inner core is subadiabatic.},
  keywords = {{N}umerical solutions ; {I}nstability analysis ; {S}eismic anisotropy ; {H}eat generation and transport},
  booktitle = {},
  journal = {{G}eophysical {J}ournal {I}nternational},
  volume = {194},
  numero = {3},
  pages = {1310--1334},
  ISSN = {0956-540{X}},
  year = {2013},
  DOI = {10.1093/gji/ggt202},
  URL = {https://www.documentation.ird.fr/hor/{PAR}00010825},
}